In vitro activity of antimicrobial agent combinations against Brucella melitensis isolates by E test

S. Kaya Firat, B. Oral, F.S. Erdinc, M.A. Yetkin, N. Tulek, A.P. Demiröz

Author address: 

Ankara, Samsun, TR


Objectives: Brucellosis is a zoonotic disease seen world-wide including Turkey. The management of the disease is difficult sometimes because of the intracellular localization of the Brucella species. Antibiotics that penetrates into the macrophages should be used in combination. In our study in vitro activities of streptomycin, tetracycline and rifampicin were investigated. Methods: In vitro activities of antimicrobial agent combinations were tested against Brucella melitensis strains isolated from 30 patients treated at Infectious Diseases and Clinical Microbiology Department of Ankara Research and Training Hospital between 1999 and 2002. In vitro effectiveness of streptomycintetracycline, rifampicin-tetracycline and streptomycin-rifampicin combinations were tested by E test method. The interactivity of in vitro combinations were evaluated as synergism, indifference and antagonism depending on the conclusions of FIK index calculated for each strain. Results: Synergism was found in 20 strains (66.7%) with streptomycin-tetracycline combination, in 26 strains (86.7%) with rifampicin-tetracycline combination and in 18 strains (60%) with rifampicinstreptomycin combination. Antagonism was found with rifampicin-streptomycin combination in only one strain. The rate of synergy of rifampicin-tetracycline combination was found higher compared to other combinations and this difference was statistically significant. We found that the rifampicin-tetracycline combination was the most effective combination in vitro. Conclusion: Although routine antimicrobial susceptibility testing for Brucella isolates is not recommended, in case of treatment failure, relapses and reinfection synergy test with E test may be helpful for treatment approach.

abstract No: 


Full conference title: 

16th European Congress of Clinical Microbiology and Infectious Diseases
    • ECCMID 16th (2006)